The invention relates to metrology devices and, in particular, to a metrology device with a programmable smart card.
Metrology devices, or meters, can be used to measure electricity, water, gas, and other commodities, and can be found in metering applications such as parking meters, payphones, weighing machines, etc. A typical metrology device simply measures a duration, frequency, or amount of a particular commodity and reports what was measured.
Referring to FIG. 1, a prior art meter 10 typically has a central control circuit 12 which is connected to a metrology unit 14, an I/O unit 16, and a display unit 18. The control circuit 12 has a meter operating system running thereon which controls the operation of the meter 10. The metrology unit 14 is connected to one or more sensors 20 which detect the commodities to be measured, e.g., electricity. The metrology unit 14 measures the commodity detected by the sensor 20 and makes this information available to the control circuit 12. In some meters, the control circuit 12 actually performs the function of the metrological unit 14 instead of having a separate metrology unit 14 perform the function. The I/O unit 16 typically includes a keypad or buttons and allows a user to input predefined commands to the meter 10. For example, a user wanting to see how much electricity was consumed last month would simply push the appropriate buttons or otherwise enter the appropriate commands, and the control circuit 12 would retrieve the desired information and display it on the display unit 18. The display unit 18 may be, for example, an LED, LCD, or other types of displays.
Typically, the accuracy of each meter is tested and certified by an appropriate certification agency before the device is put into use. The certification is good for the entire life of the meter, which is typically around 10 years. Certification requires formal xe2x80x9ctypexe2x80x9d0 testing of any change to a meter""s composition or functionality which may affect the meter""s metrological function in order to ensure that there are no adverse effects to the meter""s accuracy or performance.
Prior art applications have attempted to add functionality to the applications by adding smart cards. For example, Schlumberger""s xe2x80x9cGSMxe2x80x9d mobile telephone products now have a Java programmable smart card in the handsets to identify subscribers and provide information about their service providers. However, it is the GSM xe2x80x9cnetworkxe2x80x9d that performs the metrological functions and not the GSM handset. A payphone has been developed by Schlumberger Payphones that has a Java Virtual Machine incorporated within the payphone""s operating system which allows the payphone to interpret and run Java applications. However, the Java Virtual Machine is then a part of the payphone""s operating system as opposed to being a separate and isolated function. Other applications include utility prepayment meters that have removable smart cards which function as transport devices for payment information and allow entry of payment and tariff into the meter. Smart cards, generally, are used for a variety of applications including electronic game cards, bank cards, and identification badges. The smart cards are typically encased in a tamper-resistant, plastic or metal housing about the size of a credit card and contain one or more embedded integrated circuit devices. The functionality of these smart cards, however, are usually predefined at the time they are manufactured.
It would be advantageous to add secure programmability to a meter in order to expand the meter""s functionality without interfering with the meter""s metrological functions.
The invention relates to adding a programmable smart card to a metrology device to expand the device""s functionality while still maintaining independent operation of the device.
In general, in one aspect, the invention relates to a metrology device comprising a metrology unit, a control circuit connected to the metrology unit, and a smart card interface connected to the control circuit. The control circuit is configured so as to be able to communicate with a programmable smart card through the interface. In one embodiment, the control circuit is configured to communicate with a Java programmable smart card. In another embodiment, the smart card interface is ISO 7816 compliant. In another embodiment, the smart card interface enables full-duplex communication between the smart card and the control circuit. In another embodiment, the control circuit is able to initiate communication with the smart card. In yet another embodiment, the control circuit is configured to send commands to the smart card. In yet another embodiment, the control circuit is configured to execute commands received from the smart card. In yet another embodiment, the control circuit is configured to select an application to be run on the smart card.
In general, in another aspect, the invention relates to a metrology system comprising a programmable smart card, and a metrology device connected to the smart card and configured to communicate with the smart card. In one embodiment, the metrology device comprises a metrology unit, a control circuit connected to the metrology unit, and a smart card interface connected to the control circuit. In another embodiment, the system further comprises a metrology device housing, wherein the smart card is housed within the housing. In yet another embodiment, the smart card is selectively removable from the housing. In yet another embodiment, the system further comprises a meter operating system that controls the operation of the meter, wherein the meter operating system is isolated from a smart card operating system. In yet another embodiment, the smart card is a Java programmable smart card.
In general, in another aspect, the invention relates to a programmable smart card comprising a storage unit configured to persistently store a program to be run on the smart card, a memory unit configured to temporarily store a program to be run on the smart card, and a microcontroller connected to the storage unit and memory unit and configured to selectively execute a metrology related function. In one embodiment, the smart card is a Java programmable smart card. In another embodiment, the microcontroller executes the metrology related function as a native function. In another embodiment, the microcontroller retrieves the metrology related program from a library of available programs.
In general, in another aspect, the invention relates to a method of operating a metrology device with a smart card, the method comprising initiating communication with the smart card, selecting an application to be run on the smart card, and sending commands to the smart card. In one embodiment, the method further comprises receiving commands from the smart card. In another embodiment, the method further comprises receiving the smart card into the metrology device. In yet another embodiment, the method further comprises performing a metrological function independent of the smart card. In yet another embodiment, the method further comprises providing a result of a metrological function to the smart card. In yet another embodiment, the method further comprises allowing the selected application to run on the smart card independently of the metrology device.
Advantages of the invention include at least the following: the addition of self-contained and secure programmability and functionality to a meter; independent operation of the meter with or without the programmability or functionality; and isolation of the meter""s operation system. Other advantages will become apparent from the following description and from the claims.